The present invention relates to an image forming apparatus such as a copying machine, and more specifically to an image forming apparatus capable of indicating a range for image formation on an original table.
Image forming apparatuses, such as copying machines, have recently been put to practical use which indicate a copiable range on their original table.
In one such conventional apparatus, an original table made of transparent glass is placed on the top of its housing. An original scale with graduations is attached to one side of the table. Underlying the scale, a pair of pointers are moved in the longitudinal direction of the scale by a suitable drive source. The pointers indicate the copiable range on the table when they stop at their respective predetermined positions relative to the scale. Based on this indication, an operator sets an original on the table, holding it against a side edge of the scale. Thereafter, he or she puts an original cover on the original and depresses a copy key, thus starting a copying operation.
In this prior art apparatus, however, the initial positions of the pointers are determined by moving the pointers toward their corresponding ends of the original scale so that either of them turns on a microswitch provided in the vicinity of an end of the maximum copiable range indicated by the pointers. Thus, the apparatus requires many components, resulting in an increase in cost.
Thereupon, the microswitch is replaced with a stopper, and a pulse motor is used as the drive source for the pointers. According to this arrangement, either of the pointers is caused to move to a position abutting the stopper so that the motor is compulsorily stopped despite the input of driving pulses.
When stopped in this manner, however, the pulse motor would produce a great noise.